The platform is more than just JS, and React has plenty of stuff going on that is "magic" enough to be no different for me than the abstraction of a DSL. How is the cost-benefit better for React when I keep seeing developers who actually try other frameworks have their minds blown at how much easier it is to do the same things?
The CSS skill loss is very real, particularly with the number of straight-to-React bootcamps that barely touch on it and the insistence on using CSS-in-JS which makes it way harder for people to explore a production website and learn the fun way. I'm not some HTML/CSS purist, and React was a big step forward for the industry, but now its time is past and we have way better alternatives.